INTRODUCTION. 7 



hydrogen as water, a series of acids with decreasing amounts of 

 carbon are obtained, and in this way we may, by properly directed 

 combination of reductions and oxidations, pass from a body of the 

 aromatic series to a body of the fatty series, and then to substances 

 in which the amount of carbon decreases, until the final products 

 of animal exchange are reached. 



That reduction processes occur in the organism has already been 

 stated, and in the following pages special examples of these are 

 given. As DRECHSEL has also found that the same electro-syn- 

 theses (of urea and phenol-sulphuric acid) are produced by the 

 continuous as well as by the alternating current, and since the 

 occurrence of galvanic currents in the body has been positively 

 shown, DRECHSEL concludes that not only do syntheses, but also 

 the combustion of foods and constituents of the tissues, take place 

 in the animal body in consequence of a quick succession of reduc- 

 tions and oxidations. 



Another attempt to explain the animal oxidations has been 

 made by M. TRAUBE. TRAUBE has brought forward powerful 

 arguments against the view that an activity of the oxygen is caused 

 by reducible substances, and he seems to believe that within the 

 organism so-called oxygen transmitters occur which act similarly 

 to nitric oxide in the manufacture of sulphuric acid where oxida- 

 tion is the result of the absorption and liberation of oxygen by 

 other substances which are themselves not directly oxidized by 

 neutral oxygen. The presence of such bodies in the animal organ- 

 ism has not thus far been proved. 



An important source of the vis viva developed in the body is to 

 be sought for in the oxidation derived from oxygen of strong poten- 

 tial energy, but also in the splitting processes ; where more com- 

 plicated chemical compounds are reduced to simpler ones, and 

 when, therefore, the atoms change from a movable equilibrium to 

 a stabler one and stronger chemical affinities are satisfied, the chem- 

 ical potential energy is transformed into vis viva (or living energy). 

 The best-known example of such a splitting process outside of the 

 animal organism is the ordinary alcoholic fermentation of sugar, 

 C 6 H 12 6 = 200, -f 2C 2 H 6 0, in which process heat is set free. The 

 animal body may also have a source of vis viva in the splitting 

 processes which are not dependent on the presence of free oxygen. 



